Method for increasing the interference resistance of a time frame reflectometer and a circuit device of implementing said method

摘要

The invention relates to methods and a circuit for increasing the interference resistance of a time frame reflectometer, in particular with respect to high frequency irradiation. A transmitted pulse (XS) is generated at a pulse repeater frequency (fprf) and coupled to a wave guide ( 4 ). A return signal (Xprobe) is returned to the wavwguide ( 4 ) by a reflector ( 14 ) which is connected to said waveguide ( 4 ) and is scanned for time-expanded representation as a reflection profile with scan pulses (XA) which are repeated at a scan frequency (fA) and measurement values are continuously calculated from said reflection profiles, expressing the distance from the reflector ( 14 ) to the process connection. The scanning frequency (fA) and the pulse repeater frequency (fprf) are altered and either the expanded time representation of the reflection profile remains unchanged or when a time change occurs in the reflection profile and said change in time expansion is and taken into account in evaluating the profile, whereby an interference factor is determined from at least one measurement of said reflection profile. In order to decide on the usability of the measurement values, an algorithm is used to calculate on the basis of the measured values said interference to the extent that sufficient measuring accuracy is attained. A circuit arrangement comprising a trigger generator ( 1 ) is used to implement the method.